Remove trivial destructor from SVal.

This enables the faster SmallVector in clang and also allows clang's unused
variable warnings to be more effective. Fix the two instances that popped up.

The RetainCountChecker change actually changes functionality, it would be nice
if someone from the StaticAnalyzer folks could look at it.

llvm-svn: 160444

clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h

@@ -68,7 +68,6 @@ protected:
 
 public:
   explicit SVal() : Data(0), Kind(0) {}
-  ~SVal() {}
 
   /// BufferTy - A temporary buffer to hold a set of SVals.
   typedef SmallVector<SVal,5> BufferTy;

clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp

@@ -559,7 +559,6 @@ ProgramStateRef GenericTaintChecker::postScanf(const CallExpr *CE,
   if (CE->getNumArgs() < 2)
     return State;
 
-  SVal x = State->getSVal(CE->getArg(1), C.getLocationContext());
   // All arguments except for the very first one should get taint.
   for (unsigned int i = 1; i < CE->getNumArgs(); ++i) {
     // The arguments are pointer arguments. The data they are pointing at is

clang/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp

@@ -3168,7 +3168,7 @@ bool RetainCountChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
     // If the receiver is unknown, conjure a return value.
     SValBuilder &SVB = C.getSValBuilder();
     unsigned Count = C.getCurrentBlockCount();
-    SVal RetVal = SVB.getConjuredSymbolVal(0, CE, LCtx, ResultTy, Count);
+    RetVal = SVB.getConjuredSymbolVal(0, CE, LCtx, ResultTy, Count);
   }
   state = state->BindExpr(CE, LCtx, RetVal, false);